Safety pilot switch



A.J.O'DAY ETAL 3,465,665

SAFETY PILOT SWITCH Sept. 9, 1969 2 Sheets-Sheet 1 Filed Feb. 15, 1968 I zrJ 010g Se t. 9, 1969 A. J. ODAY ET SAFETY PILOT SWITCH 2 Sheets-Sheet 2 Filed Feb. 15, 1968 United States Patent 3,465,665 SAFETY PILOT SWITCH Arthur J. ODay, Lake Geneva, Wis., and Dennis J. Ricker, Dayton, Ohio, assignors of seventy-five percent to Arthur J. ODay, Lake Geneva, Wis., and twelve and one-half percent each to Dennis J. Ricker and George Gelofcsak, both of Dayton Ohio Filed Feb. 15, 1968, Ser. No. 705,732 Int. Cl. F241? 11/00 US. Cl. 98-1 5 Claims ABSTRACT OF THE DISCLOSURE This system is directed to a safety control system for the ventilation of compartments wherein the volume of air in the compartment is susceptible to becoming mixed with a flammable gas, and wherein the compartment contains an electrically energizable device which may inadvertently cause an arc or spark to ignite or explode the gas in the compartment. The control system includes a ventilating fan and a timing device which are initially energized by a fan control switch. The timing device senses a predetermined period of time and thereafter energizes a relay the contacts of which are connected in series with the electrically energizable device in the compartment. Therefore the electrically energizable device within the compartment cannot be energized until the compartment has been sufiiciently ventilated.

BACKGROUND OF THE INVENTION Field of the invention This invention relates generally to a safety control system which prevents energization of electrical components within a compartment until such time that the compartment has been sufficiently ventilated of unwanted flammable gases which may have inadvertently accumulated therein. Specifically, the present invention is directed to a time delay control system which prevents energization of electrical components positioned within a compartment until a predetermined period of time has elapsed to insure sufficient ventilation of the compartment.

Description of the prior art The present invention has particular utility when used in conjunction with ventilating the engine compartment and bilge area of a boat. Heretofore, engine and bilge compartments have been provided with ventilating fans which were energized by a switch located at the control console of the boat. The ventilating fan is to be energized and operating for a short period of time before the engine or engines of the boat are started. This is a safety precaution to prevent fire or explosion from occurring in these compartments should they be filled with gasoline fumes. However, should the operator fail to energize the ventilating fan, or energize the fan for too short a period before attempting to start the engine, the probability of fire is greatly increased. In fact, this is of considerable importance as many fires occurring aboard boats having inboard engines are caused by the fact that the engine compartment or bilge has not been properly ventilated before the engines were started.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a time delay device connected in circuit with the ignition or starting controls of the engine to prevent starting of the engine until a ventilating fan has been operated for a predetermined period of time.

A feature of the present invention is the use of simple Patented Sept. 9, 1969 ice and inexpensive electronic timing circuitry for sensing a predetermined period of time and thereafter allows the engine of a boat to be started.

Another feature of the present invention is the use of a silicon controlled rectifier connected in series with a control relay and connected in parallel with an electronic timing circuit thereby providing a conduction current path for the control relay and a shunt current path for the electronic timing circuit to prevent prolonged energization of the components of the timing circuit.

Briefly, the starting of an internal combustion engine within a boat is delayed by preventing completion of either the ignition circuit or the starting circuit, or both. A normally opened contactor, or contactors, prevent the completion of the circuit. The contactors are associated with a solenoid operated relay. The solenoid operated relay is energized by a silicon controlled rectifier connected in series therewith. The silicon control-led rectifier remains non-conductive until a predetermined time interval is sensed, during which time a ventilating fan is operated. The time delay is controlled by an electronic timing circuit including a resistor capacitor charging network associated with the emitter electrode of a unijunction transistor. When the capacitor of the charging network has charged to a predetermined value, the unijunction transistor is rendered conductive. The gate electrode of the silicon controlled rectifier is connected to the unijunction transistor and is rendered operative in response to the conduction thereof. Conduction of the silicon controlled rectifier energizes the solenoid valve and closes the contactors to able the ignition circuit or starting circuit of the engine. An airflow detection switch may be incorporated in the circuit to prevent the timing circuit from starting its timing cycle until an actual ventilating condition is sensed. An indicating lamp may be incorporated V in the circuit and connected in parallel with the solenoid BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a side elevational view of a boat with portions broken away to show the environment wherein the present invention can be used;

FIGURE 2 is a diagrammatic representation of a control console of the boat of FIGURE 1; and

FIGURE 3 is a schematic wiring diagram of the time delay control circuit constructed in accordance with the principles of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Seen in FIGURE 1 is a boat 10 having an inboard engine 11 positioned within an engine compartment 12. The bottom of boat 10 is provided with bilge compartments 13 and 14. The bilge compartments 13 and 14 may be in airflow communication with the engine compartment 12, or may be sealed therefrom. A fuel storage compartment 16 is provided over the aft bilge compartment 14 for storing the fuel necessary to power the boat. When the bilge compartments 13 and 14 are in airflow communication with the engine compartment 12, only a single ventilating system may be necessary for proper ventilation of the bilge compartments as well as the engine compartment. However, when the bilge compartments 13 and 14 are sealed from the-engine compartment 12, separate ventilating systems may be necessary. Additionally, the fuel storage compartment 16 may be in airflow communication with the bilge compartment 14, or sealed therefrom. Therefore, if the fuel compartment 16 is sealed from the bilge compartment 14, and the bilge compartment 14 is sealed from the engine compartment 12 a separate ventilating system for the fuel compartment 16 may be necessary.

For the purpose of setting forth the environment of the present invention, we will consider only ventilating the engine compartment 12 to disclose a preferred environment for the present invention.

The boat includes a flying bridge 17 located on top of the boat. The flying bridge 17 includes a control console 19 and a steering wheel 20 for controlling the maneuvering of the boat. Additionally, it will be understood that a second control station may be provided in the forward cabin compartment 18 of the boat 10. The controls of the flying bridge and of the forward cabin compartment are paralleled to allow operation of the boat from either station. Therefore, only the control console on the flying bridge 17 will be discussed in connection with the present invention.

In airflow communication with the engine compartment 12 is an air inlet duct 21 for supplying ventilating air to the compartment 12. An air outlet duct 22 has the lower end thereof positioned within the engine compartment 12 and connected to a ventilating fan 23. The ventilating fan 23 sucks in air from the intake duct 21, through the engine compartment 12, and blows the air out the duct 22, thereby providing a continuous circulating condition for ventilating the compartment 12. This action removes any gasoline fumes which may inadvertently accumulate within the engine compartment, and which fumes may ignite or explode when the engine is started.

Seen in FIGURE 2 is a portion of the flying bridge 17 showing the control console 19. The control console 19 includes the customary gauges to indicate the operating condition of the engine, as well as an ignition starting switch 24. Additionally, the control console 19 is provided with a blower switch 26 and an indicating lamp 27. Before the engine 11 can be started by the ignition switch 24, the blower switch 26 must be turned on to allow the blower 23, seen in FIGURE 1, to operate for a predetermined period of time. After the lapse of the predetermined period of time, a special circuit arrangement energizes a relay the contacts of which are connected in series with the ignition switch 24 to allow operation of the switch 24 to start the motor 11. Additionally, the indicating lamp 27 is energized to indicate to the operator that the compartment 12 has been ventilated for a sufficient time interval and that the engine can now be started. Therefore, after the indicating lamp 27 is lit, the operator can actuate the ignition switch 24 and start the engine.

For a better understanding of the novel circuit arrangement utilized to control the ventilating operation within the compartment 12 of the boat 10, reference is now made to FIGURE 3. The circuit of FIGURE 3 includes a battery 30, which may be the power supply for starting the engine 11. Connected to battery 30 is the ventilating switch 26 which, in turn, is connected to one end of the blower motor 23 for energizing the blower motor 23 when the switch 26 is closed. Also connected to switch 26 is a relay solenoid 31 and one end of the indicating lamp 27. The other end of relay solenoid 31 and of indicating lamp 27 are connected to a circuit point 34 which, in turn, is connected to an electronic timing circuit 36. Also connected to circuit point 34 is the anode of a silicon controlled rectifier 37. The silicon controlled rectifier 37 is energized at the end of a predetermined time interval sensed by the timing circuit 36 and energizes the relay coil 31 thereby closing a pair of contactors 32 and 33 associated with the coil 31. The contactors 32 and 33 may be connected in series with the ignition circuit of the en- 4 gine 11 and in series with the starting circuit of engine 11 or may be connected in series with the ignition circuit of two separate inboard engines of a boat. The timing circuit 36 includes a Zener diode 38 which serves to regulate the voltage applied to a resistor capacitor charging circuit 39. The charging circuit 39 comprises a capacitor 40, a fixed resistor 41 and a variable resistor 42. The variable resistor 42 provides means for changing the RC time constant of the charging circuit to change the amount of time delay provided by the circuit.

Unijunction transistor 43 has the emitter electrode thereof connected to the junction of capacitor 40 and resistor 41. One of the base electrodes of transistor 43 is connected to the battery 30 through a resistor 44, while the other base electrode of transistor 43 is connected to the other end of battery 30 through the switch 26, lamp 27 and relay coil 31 connected in parallel, and a resistor 45. In operation, when capacitor 40 is charged to a predetermined voltage, which voltage is indicative of time, the unjunction transistor 43 will be rendered conductive thereby applying a firing potential to the gate electrode of *silicon controlled rectifier 37 to render the controlled rectifier conductive. This action energizes relay coil 31 and closes contactors 32 and 33 to complete the circuit to start engine 11.

A current limiting resistor 46 is connected between circuit point 34 and the timing circuit 36 to limit the current flow through Zener diode 38 thereby preventing inadvertent damage to the Zener diode. An airflow switch 47 may be connected between the current limiting resistor 46 and the timing circuit 36. The airflow switch 47 is closed in response to sensing an actual airflow through either the engine compartment 12 or the outlet duct 22 to insure that not only is the ventilating motor 23 energized but is also operating.

A unique feature of the present invention is the fact that the silicon controlled rectifier 37 is connected in series with the relay coil 31 and in parallel with the electronic timing circuit 36. Therefore, when silicon controlled rectifier 37 is rendered conductive, circuit point 34 is placed at substantially the same potential as the cathode of the silicon controlled rectifier to complete the circuit path for the relay coil 31. This action shunts the timing circuit 36 to prevent additional current flow from being supplied to the timing circuit thereby reducing power consumption as well as increasing the life of the components comprising the timing circuit, thereby insuring a long accurate life of the timing circuit.

As the indicating lamp 27 is connected in parallel with relay coil 31, the indicating lamp will be energized simultaneously with the relay coil to give visual indication to the boat operator that the proper ventilating time is completed and the engine can be started.

Although a specific and preferred embodiment of the present invention has been set forth in great detail, it will be understood that variations and modifications may be effected without departing from the spirit and scope of the novel concepts of this invention.

We claim as our invention:

1. A safety control system for the ventilation of an engine compartment of a boat to prevent starting of the engine until the compartment has been sufficiently ventilated, said engine including components to cause starting of the engine, said safety control device comprising: an electrical power source; a starting switch for connecting said electrical power source to said engine components to start the engine; first means for ventilating the compartment; second means for sensing a predetermined time delay; first normally opened switch means connected between said power source and said first and second means for initiating energization of said first and second means; second switch means having a normally opened contactor connected in series with said starting switch and responsive to said second means, said normally opened contactor being closed after said predetermined time delay is sensed,

thereby allowing said Starting switch to be actuated to energize said starting components only after the engine compartment has been ventilated for said predetermined time delay, and further including third air flow switch means connected in series with said second means and responsive to said ventilating means to prevent said second means from being energized until said ventilating means is operated.

2. A safety control system for the ventilation of compartments wherein the volume of air in the compartment is susceptible to becoming mixed with a flammable gas and wherein the compartment contains an electrically energizable device, said control system comprising: an electric power source, first means for ventilating the compartment; second means for sensing a predetermined time delay; first normally opened switch means connected between said power source and said first and second means for initiating energization of said first and second means; second switch means having a normally opened contactor connected in series with the electrically energizable device in said compartment, said second switch means being responsive to said second means, said normally opened contactor being closed after said predetermined time delay is sensed, thereby, allowing energization of the electrically energizable device only after the compartment has been ventilated for said predetermined time, wherein said second switch means includes an electrically operated solenoid for actuating said contactor and wherein said solenoid has one end thereof connected to said first switch means and said means for ventilating, and the other end thereof connected to said second means, wherein said means for sensing a predetermined time delay is an electronic timing circuit including a resistance capacitor charging circuit and a unijunction transistor having first and second base electrodes and an emitter electrode, said emitter electrode connected to said resistor capacitor charging circuit for rendering said unijunction transistor conductive in responsive to said charging circuit, and further including electronic switch means which is rendered conductive in response to the conduction of said unijunction transistor thereby energizing said electrically operated solenoid.

3. A safety control system for the ventilation of an engine compartment of a boat to prevent starting of the engine until the compartment has been sufficiently ventilated, said engine including components to cause starting of the engine, said safety control device comprising: an electrical power source; a starting switch for connecting said electrical power source to said engine components to start the engine; first means for ventilating the compartment; second means for sensing a predetermined time delay; first normally opened switch means connected between said power source and said first and second means for initiating energization of said first and second means; second switch means having a normally opened contactor connected in series with said starting switch and responsive to said second means, said normally opened contactor being closed after said predetermined time delay is sensed, thereby allowing said starting switch to be actuated to energize said starting components only after the engine compartment has been ventilated for said predetermined time delay, wherein said second means includes an electrically operated solenoid for actuating said contactor and wherein said solenoid has one thereof connected to said first switch means and said means for ventilating, and the other end thereof connected to said second means, wherein said means for sensing a predetermined time delay is an electronic timing circuit including a resistor capacitor charging circuit and a unijunction transistor having first and second base electrodes and an emitter electrode, said emitter electrode connected to said resistor capacitor charging circuit to cause conduction of said unijunction transistor having first and second base electrodes and an emitter electrode, said emitter electrode connected to said resistor capacitor charging circuit to cause conduction of said unijunction transistor, and further including electronic switch means which is rendered conductive in response to the conduction of said unijunction transistor thereby energizing said electrically operated solenoid.

4. A safety control circuit according to claim 3 wherein said electronic switch means is a silicon controlled rectifier having anode, cathode and gate electrodes, said anode and cathode connected in series with said solenoid and in parallel with said electronic timing circuit, and said gate electrode connected to said unijunction transistor, whereby, conduction of said silicon controlled rectifier in response to said unijunction transistor provides a shunt current path for said electronic timing circuit to substantially eliminate current flow through said electronic timing circuit.

5. A safety control system according to claim 2 wherein said electronic switch means is a silicon controlled rectifier having anode, cathode and gate electrodes, said anode and cathode electrodes connected in series with said solenoid and in parallel with said electronic timing circuit, and said gate electrode connected to said unijunction transistor for receiving a firing pulse therefrom in response to said charging circuit, whereby, conduction of said silicon controlled rectifier provides a shunt current path for said electronic timing circuit to substantially eliminate current fiow through said electronic timing circuit while said silicon controlled rectifier is conductive.

References Cited UNITED STATES PATENTS 3,315,584 4/1967 Van Ranst 98-1 LLOYD L. KING, Primary Examiner 

